1. Technical Field
The present disclosure relates to electrosurgical instruments. More particularly, the present disclosure relates to temperature-sensing electrically-conductive tissue-contacting plates configured for use in electrosurgical jaw members and methods of manufacturing the same.
2. Discussion of Related Art
Electrosurgical instruments, such as electrosurgical forceps, are well known in the medical arts. Electrosurgery involves the application of thermal and/or electrical energy to cut, dissect, ablate, coagulate, cauterize, seal or otherwise treat biological tissue during a surgical procedure. Electrosurgery is typically performed using an electrosurgical generator operable to output energy and a handpiece including a surgical instrument (e.g., end effector) adapted to transmit energy to a tissue site during electrosurgical procedures. Electrosurgery is typically performed using either a monopolar or a bipolar instrument.
The basic purpose of both monopolar and bipolar electrosurgery is to produce heat to achieve the desired tissue/clinical effect. In monopolar electrosurgery, devices use an instrument with a single, active electrode to deliver energy from an electrosurgical generator to tissue, and a patient return electrode or pad that is attached externally to the patient (e.g., a plate positioned on the patient's thigh or back) as the means to complete the electrical circuit between the electrosurgical generator and the patient. When the electrosurgical energy is applied, the energy travels from the active electrode, to the surgical site, through the patient and to the return electrode.
In bipolar electrosurgery, both the active electrode and return electrode functions are performed at the site of surgery. Bipolar electrosurgical devices include two electrodes that are located in proximity to one another for the application of current between their respective surfaces. Bipolar electrosurgical current travels from one electrode, through the intervening tissue to the other electrode to complete the electrical circuit. Bipolar instruments generally include end-effectors, such as graspers, cutters, forceps, dissectors and the like.
Bipolar electrosurgical forceps utilize two generally opposing electrodes that are operably associated with the inner opposing surfaces of the end effectors and that are both electrically coupled to an electrosurgical generator. In bipolar forceps, the end-effector assembly generally includes opposing jaw members pivotably mounted with respect to one another. In a bipolar configuration, only the tissue grasped between the jaw members is included in the electrical circuit. Because the return function is performed by one jaw member of the forceps, no patient return electrode is needed.
A variety of types of end-effector assemblies have been employed for various types of electrosurgery using a variety of types of monopolar and bipolar electrosurgical instruments. Jaw member components of end-effector assemblies for use in electrosurgical instruments are required to meet specific tolerance requirements for proper jaw alignment and other closely-toleranced features. Gap tolerances and/or surface parallelism and flatness tolerances are parameters that, if properly controlled, can contribute to a consistent and effective tissue seal. Thermal resistance, strength and rigidity of surgical jaw members also play a role in determining the reliability and effectiveness of electrosurgical instruments.
By utilizing an electrosurgical forceps, a surgeon can cauterize, coagulate, desiccate and/or seal tissue and/or simply reduce or slow bleeding by controlling the intensity, frequency and duration of the electrosurgical energy applied through the jaw members to the tissue. During the sealing process, mechanical factors such as the pressure applied to the vessel or tissue between opposing jaw members and the gap distance between the electrically-conductive tissue-contacting surfaces (electrodes) of the jaw members play a role in determining the resulting thickness of the sealed tissue and effectiveness of the seal. Accurate application of pressure is important to oppose the walls of the vessel; to reduce the tissue impedance to a low enough value that allows enough electrosurgical energy through the tissue; to overcome the forces of expansion during tissue heating; and to contribute to the end tissue thickness which is an indication of a good seal. A variety of instruments have been developed that utilize technology to form a vessel seal utilizing a combination of pressure, gap distance between opposing surfaces and electrical control to effectively seal tissue or vessels.
Methods and systems have been developed for controlling an output of a generator, such as a radio-frequency (RF) electrosurgical generator, based on sensor signals indicative of impedance changes at a surgical site. In some systems employing changes in impedance to control the amount of electrosurgical energy applied to tissue, when the sensor signal meets a predetermined level based on a control algorithm, the system provides an end tone that indicates to the surgeon that a procedure, such as a vessel-sealing procedure, is complete. In generators employing an impedance-based control algorithm, impedance is a proxy for temperature, and there are cases where an end tone may be given when no tissue sealing has occurred because the impedance proxy was incorrect.